This research is aimed at determining the roles of naturally occurring prenatal and postnatal auditory and visual stimulation (experience) in the development of the maternal social bond in ducklings. Since it is now known that embryonic auditory experience plays an important role in the development of otherwise "innate" response to the maternal call of the species, we shall assess the plasticity of the embryo's auditory system to see if it is possible to establish a preference for an alien species maternal call by exposure to that call during embryonic development. Additionally, we shall determine whether the duckling is capable of learning subtle differences between maternal calls of its own species based on exposure during the late embryonic period. Using a newly developed peep suppression/habituation procedure (Gray & Rubel), we shall be able to find out if the loss of specificity in the species-typical repetition rate preferences in the mute, aurally isolated duckling also involves a loss of discrimination ability as well. Finally, by comparing the strength of visual imprinting in ducklings that have been visually imprinted in association with the species maternal call vs, other calls, we shall determine whether the species call plays a special role in visual imprinting. Also, we shall compare the efficacy of mere exposure, heat, and food reinforcement in the postnatal establishment of individual maternal recognition based on species-typical audiovisual stimulation. Our long-term aims involve tracing out in comprehensive behavioral, sensory stimulative, and experiential detail the embryonic and neonatal precursors to the normal manifestation of species-specific perception. We hope to continue to refine a theory of neural maturation and behavioral development which is founded on the facts derived from these studies, and which has proved applicable to other species including man. This research lies in the domians of comparative developmental psychology and ethology, providing a model for the delineation of ways in which normally occurring prenatal functioning of the neonate. As regards the sensory-stimulative factors which promote the normal or usual development of behavior, the possible interrelationships between prenatal and postnatal ontogeny are largely unknown for any species, including man.